| 摘要 |
PURPOSE:To reduce the variability of the outer diameter of a mother material for optical fiber and the fluctuation of differential pressure, by providing a gas feed pipe for a bias gas along the flow direction of an exhaust gas, by adjusting the flow amount of the bias gas so that the pressure of a reaction vessel is controlled. CONSTITUTION:The flame 5 containing finely divided particles of glass prepared by the flame hydrolyzing burner 1 is blown to the target 4 moving in the arrow direction 7 while rotating in the arrow direction 8 so that the rodlike mother material 2 for porous glass is grown. A gas is introduced along the exhaust gas 14 flowing in the exhaust pipe 13 through the gas feed device 19 in the arrow direction 21 from the gas feed pipe 20, the pressure P1 in the reaction vessel 6 is detected by the pressure detecting device 15, and this pressure P1 is compared with the standard pressure value Pr which is previously set by the controlling part 18. When it causes P1not equal to P2, an output signal is generated at the output end of the controllig part 18 and it is returned to the device 19 by feed back. When P1>Pr, the amount of gas flowing in the arrow direction 21' is increased, and when P1<Pr, the amount of gas is reduced so that the device 19 is controlled. |
